Assess the efficacy (response rate, time to progression) and toxicity of single-agent 9-AC in patients with recurrent/progressive, favorable and unfavorable histology NHL. Favorable and unfavorable groups will be evaluated separately with regard to efficacy. Conduct a pharmacokinetic and pharmacodynamic evaluation of 9-AC in patients with recurrent NHL. Formulate a preliminary pharmacodynamic dosing model for 9-AC.